Method of cleaning glass cloth



April 6, 1954 E. H. BALZ 2,674,549 METHOD OF CLEANING GLASS CLOTH Filed May 28, 1951 3 Sheets-Sheet l INVENTOR EMIL H. BALZ BY W ATTORNEYS April 6, 1954 E. H. BALZ METHOD OF CLEANING GLASS CLOTH Filed May 28, 1951 FIG- 2 GLASS CLOTH PLUS BINDER 3 Sheets-Sheet 2 SOLUTION OF OXIDIZING AGENT TREAT CLOTH WITH OXIDIZING SOLUTION AT ABOUT HEAT CLOTH TO ABOUT s50 750F CLEAN GLASS CLOTH INVENTOR EMIL H. BALZ' lag "WM ATTORNEYS April 6, 1954 E. H. BALZ METHOD OF CLEANING GLASS CLOTH Filed May 28, 1951 GLASS CLOTH PLUS BINDER SOAK GLASS IN CHLORATE SOLUTION FOR V2 TO I HOUR HEAT CLOTH TO 650F.

TO 750"? FOR 2 MINUTES TO REMOVE BINDER CLOTH KCL PLACE CLOTH m HYPOCHLORITE SOLUTION AND sum: F02 ABOUT WASH CLOTH WITH WATER UNTIL MSHWATER PH IS 7.5 T0 8.0

DRY GLASS CLOTH I CLEANED GLASS CLOTH 3 Sheets-Sheet 3 5% CHLORATE SOLUTION WITH WETTING AGENT AT |50 F.

0.5 T0 I.5% SODIUM HYPOCHLORITE AT PH OF IO'II HOT WATER I50 E I70 E INVENTOR EMIL H. BALZ ATTORNEYS Patented Apr. 6, 1954 METHOD OF CLEAN IN G GLASS CEOTH Emil H. Balz, Waterville, 0hio,.assignor. to Glass Fibers Inc.,.Waterville, Oliio, a corporation of Application-:May28; .1951, Serial No.- 2285624 14 Claims. 1

This invention relates to glass.- cloth. More particularly the inventionrelatesto a treatment for glass cloth to render the same useful in the making of laminations with resinous materials. In the production of glass cloth the glasscom position is first made molten andcaused to now from extremely smallorifices from which it is: picked up by a revolvingdrumzor an air or-high' pressure steam blast and pulled into long fine fibers. The individual fiber, is smooth,..substan tially cylindrical and normally has a diameter of about .00621 to .O0O40.inch. The fibers mayv then be groluped in suchfashion asto form a thread of parallel, fibers and thereafter a group of the continuous,- fibers is sent ontto thetextile machines for weaving intotclotha In order to minimize frictioniin processing, the fibers while they arebeing. drawn. out are treated with a water dispersionof a lubricant or binder material prior to.- formation of the groups. This-binder material, whichzgenerally consists of a vegetable lubricating oil, starch and.

very small amountsof Wetting,and dispersingv agents, etc., coats-the fibers'an'd-remains thereon in the finished glass clot to the extent of about 1.5%" to 2.0% on the dryfinished glass cloth.

by; weight The presence of this binder. aids inthe textile operation but seriously affects the: ability,

laminateswith' other:

of the glass cloth to'form materials, such as syntheticresins. Accordinglyi when it is desired to form such laminatestreatment of the glass cloth to remove the binderuma'r-v terial is required in order to. obtain satisfactory adhesions between the clothiand the resin.

Present known methods for theremoval of the binder requireamong other steps-the treatment of the cloth at temperatures of thezorder of 600 to 700 F. for prolonged periods, generally;

55 to 60 hours. Such. methods; otfcourse; sex-i ously hinder production: require:-anLeXceSsiVe amount of equipment for a given p1-o:luction, and in the overall-areexceedingly expensive:

The present invention contemplates the pro vision of a novel method--for-theremoval ofthe binder material from the glass clcthxutilizin'ga short moderate heat cycle.-

The invention further contemplatesamethod.

of providing ascrupulouslyrlean glass cloth surface particularly suitable. forqcombiningzwith I resinous compositions..

The invention also contemplates the provision. of a production method-foev the icleaningz ofi-thex: glass cloth whichazeliminatesetheznecessity101221 The binder is presentthe glass cloth containing the oil-starch binder material with a strong oxidizing agent and thereafter heating the cloth for a matter of about /2 minute or slightly longer at moderate temperatures. The treated binder is reacted by this treatment and in efiect isburnedfrom the glass cloth.

In the practice of theinvention the glass cloth is first treated with a strong chlorate solution, that is about 3- to 10% by Weight of chlorate, atv a temperature of about 150 F. Detergents or wetting. agents are employed in the chlorate solution to assist in the penetration and Wetting of the cloth.-

The wet cloth'maythen be subjected to the action of the heating step to effect removal of the binder. The chlorate, which is of itself stable at temperatures of up to about 900 F. will in the presence of the binder at the heating temperature break down, releasing oxygen, which actson the binder to decompose it and remove it from the cloth. Anyslight discoloration present on thecloth due to decomposed binder may thereafter be eliminated by subjecting thecloth to the action of a bleaching agent, the excess of which may thenbe removed if necessary by washing. with water.

The treatment of the invention is adaptable to all oil-starch binder materials and in substantially all proportions of these components. The oil of the binder is generally a lubricating oil of vegetable origin, such as caster, hydrogenated cottonseed,-olive and coconut. Highly unsaturated oils due to their instability to light are not usually employed in the lubrication of'fibers for glass cloth manufacture, but if so employed would also be removable from such cloth by the process of the invention. The starch of the binder may be of any of the normal starches of commerce and may include the slightly hydrolyzed or dextrinizedinat'eri'als. In addition to these primary components the binder may contain, in extremely small amounts, one'or more substances such as gelatine, borax, polyvinyl alcohol; a cationic agent or other wetting and dispersing compounds.

These ingredients are set-forth by way of il1uctrati'ononly since the inventive concept is cable to: the-removal of all components after treatment bythe oxidizing agent are in such a :condi-tion as v to render themreadil removable' from the" cloth bythe ignition step dewhich appli-- 3 scribed in detail hereinafter. In most instances these secondary components may of course be readily selected in the first instance in order that the desired end be achieved.

The oxidizing agents which are particularly suitable for the process of invention include the chlorates of sodium, potassium, calcium, barium, strontium and magnesium. The prime requirements of the oxidizing agent for production purposes are that the agent have strong oxidizing powers, be adaptable to simple production equipment, not deleteriously affect the glass and be soluble at moderate temperatures.

Bleaching of the cloth where necessary may be effected in any suitable medium which does not attack the glass cloth, the prime purpose of this step being to effect complete cleaning of the glass surface by removing any chloride present and any discoloration due to binder residue. Thus exposure of the cloth to an oxidizing atmosphere, such as oxygen gas, may effectively be employed. However, it is generally preferred for production purposes to utilize a bleaching solution, such as sodium hypochlorite in water. Other specific bleaching agents may be used subject to the limitations in their selection that they do not attack the glass and that for production purposes they leave little or no residue that may not be washed out with water. Calcium hypochlorite may, for example, be employed, but is somewhat more difficult to wash from the fabric.

I have found that rather moderate temperatures of 650 F. to 750 F. may be used to burn the binder from the treated glass cloth and that the time of exposure to the heat need only be very short, that is, in the range of about /2 to 1 /2 minutes. For example, a glass cloth containing a binder material to the extent of about 1.8% on the weight of the cloth, the binder consisting essentially of 16 parts of starch and 2 parts of hydrogenated cottonseed oil and negligible amounts of other decomposable material was completely cleaned leaving no residue, by exposure to an oven temperature of 700 F. for about one minute. At an oven temperature of about 750 F. it was found to be possible to cleanse the same cloth in about /2 minute, only a very slight residue remaining on the cloth after ignition, this residue being readily removed by supplemental treatment with a bleaching agent such as hypochlorite. The treatment of invention therefore permits of a very short operating cycle to be described more fully in the specific example detailed hereinafter.

Detergent and wetting agents particularly useful in the oxidizing solution are those such as Triton N-lOO which is a concentrated wetting agent and detergent designed primarily for use in the textile trade. Such an agent assists in the wetting and penetration of the cloth binder which of itself is somewhat water repellent due to the oil content thereof. Triton N-100 is a concentrated wetting agent and an aryl alkyl polyether alcohol soluble in all proportions in cold water and. soluble in most organic compounds.

The surface of the glass clot-h thus cleaned acquires a hydroxyl group since the glass is hydrolyzed by the action of the alkaline bleaching agent. The presence of this anion assists adhesion between the glass and the resin layer to be applied thereto, and is of a particular benefit where a cationic agent such as methacrylate chromic chloride (Volan) is applied to the glass to form thereon an adsorbed film containing reactive double bonds. which combine readily with organic materials such as the polyesters. The formation of these laminates is of itself known to the art and forms no part of the present invention. However, the subject matter contained in my copending application, Serial No. 235,161, filed July 5, 1951, is directed to an improvement of the known process of laminate formation. This application is also related to Serial No. 228,623, filed May 28, 1951.

The invention will be more fully understood by reference to the following detailed description and appended drawings wherein:

Figure 1 is a diagrammatic representation of apparatus used in the preferred embodiment of the invention.

Figure 2 is a fiow sheet illustrating the process;

of invention; and

embodiment of the process of invention.

Referring to Figure 1, there is shown a roll of glass cloth I produced from standard 13 glass,, the fibers of which during manufacture were treated with an aqueous binder material consist-- ing by weight of about 2% of hydrogenated cot-- tonseed oil (Pureco), about 8% of partially dextrinized starch (Globe gum), about 06% of gela tin, about .13% of polyvinyl alcohol, about .2% of Tween 81 (partial esters of fatty acids and hexitolanhydrides combined with polyoxyethylene chains), about .4% of onyx cation X (fatty imidazoline derivative), the balance being water and a very small amount of borax to bring the pH of the dispersion into the range of 6.0 to 6.6. This binder material, minus the water content, is present to the extent of about 1.8% by weight on the dry glass cloth roll shown at l.

The roll of glass cloth I is shown mounted upon a stand 2 and may be appropriately unreeled and passed over an idler roller 3, into a tank 4 containing an aqueous solution of potassium chlorate having a chlorate concentration of about 5%, approximately .05 to 0.1 of 1% by weight of the solution of Triton N- wetting agent an aryl alkyl polyether alcohol soluble in all proportions in cold Water, as detergent, indicated generally at 5. This treatment serves to remove a portion of the starch and soluble borax and gelatin from the cloth and to render the binder remaining susceptible to the temperature treatment described hereinafter. The cloth is rerolled in the solution on stand 6 and permitted to soak for about /2 to 1 hour, whereupon it is removed from the chlorate solution and stored as at 1 to await further processing. It is clear that a number of rolls may be subjected to the action of the chlorate at one time as indicated at 8, 9 and that a small storage space indicated generally at It will accommodate a considerable number of treated rolls.

The cloth, preferably while still wet with the oxidizing solution, may be unreeled from a stand II and passed directly to oven 18. Alternatively the cloth prior to entering the oven may be further wet with oxidizing solution by passing the fabric continuously over rolls [2, I 3 and I4 and under sprays indicated generally at 15. These sprays, if utilized, are supplied with oxidizing solution 5 in which case a pump (not shown) is provided to move the liquid from tank 4 to these sprays. Solution 5 will contain dispersed starch as well as the primary ingredients of the solution, and the presence of the dispersed starch enhances the spray action. Where the spray of oxidizing solution is employed the spent spray liquid may be recirculated to tank 4.

The cloth, treated with the oxidizing agent either by soaking alone, or by soaking plus the spray treatment noted, is then passed'under a spreader roller El and thence to oven I8, which operates at'a temperature of approximately 650 F. to 750 F. and wherein a conveyor indicated at E9 driven through power means denoted at Zil supplies motive power to the cloth. The oven has an overall length or" about 12 feet and the conveyor may be operated at controlled adjustable speeds of between about 2 to 30 feet per minute, and in the instance under consideration the cloth and conveyor were driven at about 12 feet per minute, the cloth assuming in the latter part of the oven traverse atemperature of about 600 F. to 650 F. It may be noted that generally it is desirable to induce movement of the cloth by providing motive means on one or more of the rolls over which the cloth passes, as will be understood by one skilled in the art.

The chlorate treated binder, including the polyvinyl alcohol, cation X and dispersingagents present, it has been found, will be driven ofi completely by the spraying and igniting action under the conditions indicated above, which as may be readily derived from the foregoing, involves the application of heat to the cloth for only about one minute.

In a further embodiment of the invention the chlorate treated cloth was passed to the oven operating at a temperature of about 700 F. and an oven conveyor speed of about 20 to 24 feet per minute and only a trace of binder remained on the cloth after the heat treatment. Under this condition the heated glass cloth may be passed continuously into a tank 2i containing a 0.5% aqueous solution of hypochlorite having a temperature of about 75 to 85 F.

Preferably the cloth is wound on reel 27 in the solution indicated at 22 and allowed to soak therein for about to 1 hour. Alternatively the cloth may he simply passed through the hypochlorite solution and stored as indicated generally at 23 in which case the storage time should also be approximately 30 minutes.

Upon completion of the bleaching treatment the excess bleaching agent is washed from the cloth with water having a temperature in the range of 150 to 170 F. by passing over rolls 24, and thereafter dried, and a completely cleaned glass cloth is attained in an overall production time for a given roll of less than about to 3 hours.

The cleaned glass cloth thus produced will laminate readily with silicone resin and when the a cleaned cloth is first treated with a cationic agent such as Volan, as discussed briefly hereinbefore, a bond with the polyesters may be effected.

in yet another embodiment of the invention the glass cloth may be treated directly with a spray of a water solution containing approximately 5% chlorate directed onto the cloth by means oi the nozzles indicated generally at I 5 in Figure 1. In this instance soaking of the rolled cloth in the chlorate solution is not necessary and the action of the spray removes a proportion of the binder material from the cloth, the balance of the binder being removed by the action or heat as noted hereinbefore. In this instance the spray solution for reasons of economy is preferably recirculated in which case the spray will contain a quantity of dispersed starch, which as noted hereinbefore assists in the removal of the binder.

Accordingly it is clear that. by suitable regulation of the heating conditions, cloth containing binder material treated with an may be suitably cleaned by a short moderate heat cycle.

While the production time for a given roll of cloth will vary somewhat with particular operating conditions and equipment available, it will be appreciated that the complete treatment time of less than 3 hours is a material improvement over the present practice wherein a matter. of several days is required for the completeprocedure.

In each of the detailed examples set forth hereinbeiore, the chlorates of sodium, magnesium, strontium, barius or calcium may be substituted for the potassium chlorate. rides resulting from the decomposition of these chlorates similarly to potassium chloride have a melting point in excess of the temperature range employed in the invention, and accordingly no possibility of fusion with the glass exists.

All glass compositions suitable for the production of glass fabrics may be employed in the process of invention and the glass will not be affected thereby. Particularly it should be. noted that no decrease in strength of the fabric occurs during the treatments set .forth.

It is to be understood that other oxidizing agents may be substituted for those specifically set forth hereinbefore, that the time and temerature of heating and selection of bleaching aguits are susceptible to modification andv that the equipment and other factors may be altered to adapt them to dififerent usages and conditions and, accordingly it is desired to comprehend such modifications within this invention as. may fall within the scope of the appended claims.

I claim:

1. in a method of removing oil-starch binder material from glass cloth the steps of impregnating the cloth with an aqueous solution of a heat decomposable chlorate selected from the group consisting of the alkali and alkaline earth metal chlorates which chlorate is capable of liberating oxygen upon heat decomposition, removing the cloth from the solution, and. heating the impregnated cloth to a temperature sufiicient to decompose the said chlorate and said binder material.

2. In a method of removing oil-starch binder material from glass cloth thesteps of impregnating the cloth with an aqueous solution of av heat decomposable chlorate selected from the group consisting of the alkali and alkaline earth metal chlorates which chlorate is capable of liberating oxygen upon heat recomposition, removing the cloth from the solution, heating the impregnated cloth to a temperature sufficient to decompose the said chlorate and said binder material, and bleaching the cloth to remove any residue remaining thereon.

3. In a method of removing oil-starch binder material from glass cloth the steps of impregnating the cloth with an aqueous solution containin by weight about 3 to 10 percent of potassium chlorate, removing the impregnated cloth from the solution, and thereafter heating the cloth to a temperature of about 650750 F. to decompose the potassium chlorate and the binder material.

4. In a method of removing oil-starch binder material from glass cloth the steps of impregnating the cloth with an aqueous solution containing by weight about 3 to 10 percent of potassium chlorate, removing the impregnated cloth from the solution, thereafter heating the cloth oxidizing agent,

The chlo-- to a temperature of about 650-750 F. to decompose the potassium chlorate and binder material, and then bleaching the cloth to remove any residue remaining thereon.

5. In a method of removing an oil-starch binder material from glass cloth, the steps of imprenating the cloth with an aqueous solution of potassium chlorate, removing the impregnated cloth from the solution, and thereafter heating the cloth to a temperature of about 600 F. to 650 F. to decompose the potassium chlorate and binder material.

6. In a method of removing oil-starch binder material from glass cloth the steps of impregnating the cloth with an aqueous solution of potassium chlorate, removing the cloth from the solution, and thereafter heating the cloth to a temperature of about 650 F. to 750 F. to decompose the potassium chlorate and binder material, and then bleaching the cloth to remove any residue remaining thereon.

'7. A method of cleaning glass cloth from oilstarch binder material comprising the steps of impregnating the cloth with an aqueous solution containing about 3-10 percent by weight of potassium chlorate for about one hour, removing the cloth from the solution, heating the cloth to about 650 to 750 degrees Fahrenheit for about one minute to decompose the potassium chlorate and burn off the binder material, soaking the cloth in an aqueous solution of sodium hypochlorite at a pH of about to 11 for about one hour, and washing the cloth to remove any excess sodium hypochlorite remaining thereon.

8. In a method of removing oil-starch binder material from glass cloth the steps of impregnating the cloth with an aqueous solution containing about 3-10 percent by weight of a metal chlorate selected from the grou of sodium, potassium, magnesium, calcium, barium and strontium chlorates, removing the cloth from the solution, thereafter heating the cloth to a temperature of at least that of the decomposition point of the chlorate impregnated in the cloth and below that of the fusion point of the chloride produced by the decomposition of the chlorate thereby liberating oxygen and decomposing the binder material, and then bleaching the cloth to remove any residue remaining thereon.

9. In a method of removing oil-starch binder material from glass cloth the steps of impregnating the cloth with an aqueous solution containing about 3-10 percent by weight of potassium chlorate at a temperature of about 150 F., removing the cloth from the solution, and thereafter heating the impregnated cloth to a temperature of about 650 F. to decompose the potassium chlorate and binder material.

10. In a method of removing oil-starch binder material from glass cloth the steps of impre nating the cloth with an aqueous solution containing about 5 percent by weight of potassium chlorate at a temperature of about 150 F. for about /2 to 1 hour, removing the cloth from the solution, and thereafter heating the impregnated cloth at a temperature of about 700 F. for about one minute to decompose the potassium chlorate and binder material.

11. In a method of removing oil-starch binder material from glass cloth the steps of impregnating the cloth with an aqueous solution containing about 5 percent by weight of potassium chlorate at a temperature of about 150 F. for about /2 to 1 hour, removing the cloth from the solution, heating the impregnated cloth at a temperature of about F. for about one-half minute, and thereafter bleaching the cloth to remove any residue remaining thereon.

12. In a method of removing oil-starch binder material from glass cloth the steps of impregnating the cloth with a spray of a water solution containing about 5% potassium chlorate and thereafter heating the cloth in air at a temperature of about 650 to 750 F. to remove the binder material therefrom.

13. In a method of removing binder material from glass cloth the steps of impregnating the cloth with a spray of a water solution containing about 5% of potassium chlorate and dispersed starch, removing the cloth from the spray, and thereafter heating the cloth in air at a temperature of about 650 F. to 750 F. to remove the binder material therefrom.

14. In a method of removing binder material from glass cloth the steps of soaking the cloth in a water solution containing about 3-10 percent by weight of potassium chlorate at a temperature of about F., removing the cloth from the solution, spraying the cloth with a potassium chlorate solution containing starch, thereafter heating the cloth at a temperature of about 650 F. to 750 F. in air to remove the binder material therefrom, and washing the cloth with wa er.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,540,491 Milliken June 2, 1925 1,578,933 Smith Mar. 30, 1926 

1. IN A METHOD OF REMOVING OIL-STARCH BINDER MATERIAL FROM GLASS CLOTH THE STEPS OF IMPREGNATING THE CLOTH WITH AN AQUEOUS SOLUTOIN OF A HEAT DECOMPOSABLE CHLORATE SELECTED FROM THE GROUP CONSISTING OF THE ALKALI AND ALKALINE EARTH METAL CHLORATES WHICH CHLORATE IS CAPABLE OF LIBERATING OXYGEN UPON HEAT DECOMPOSITION, REMOVING THE CLOTH FROM THE SOLUTION, AND HEATING THE IMPREGNATED CLOTH TO A TEMPERATURE SUFFICIENT TO DECOMPOSE THE SAID CHLORATE AND SAID BINDER MATERIAL. 